The written language you use changes when you are hiding a secret — even in text, email, or instant message correspondence.

People who are withholding secrets corresponded more with friends and family compared with their honest counterparts, but these interactions are more superficial, the researchers found. Changes in language linked to secret-keeping are slight, but are able to be detected by specific computer programs.

The research was led by James Pennebaker, Psychologist and language analysis expert at the University of Texas at Austin and was presented at the 2013 American Psychological Association conference in Honolulu on July 31. These studies are preliminary and not peer-reviewed.

Pennebaker writes [PDF]: "We are finding that the 'junk words' people use — articles, pronouns, prepositions — are powerful markers of their linguistic styles and these styles are often linked to other aspects of their lives."

Studying secrets

Pennebaker's first study was conducted using a year's worth of emails from mid-20s female participants. He analyzed the language of the emails based on if the person was in a depressive episode, and if the recipient of the email knew about the depression.

The researchers saw that the depressed patients keeping their depression a secret sent more and longer emails, hid their negative emotions and accentuated their positive emotions, used more self-reflective words.

They were less likely to match their language to the language of their correspondent, and put together these factors made them unable to connect with their correspondents as well.

In a second study, the researchers specifically picked out 62 adults who were keeping a secret (they didn't tell them that was why they were chosen). They screened their emails for the next year, screening for which were relevant to the secret in question.

They saw that when the subject was corresponding with a person relevant to the secret in question, they used more deceptive language, and more negative emotions.

The big secret

These associations aren't detectable by the human brain, but researchers can use a computer program can use these findings to analyze emails and sniff out liars.

"To understand secrecy, you have to look at the person in the context of his/her social network," Pennybaker said. "Secrecy is associated with a superficial boost in number of interactions (which reflects greater hyper vigilance). At the same time, these increased interactions are not closely connecting with others."

He concluded: "This work points to the fact of how a big secret affects most everyone in the secret-keepers network."